A liquid crystal display (LCD) panel is a device that blocks or allows light (controls on and off of display) through controlling the orientation of liquid crystal molecules having birefringence. The modes of liquid crystal orientation for LCDs include the TN (twisted nematic) mode in which liquid crystal molecules with a positive dielectric anisotropy are oriented such that the molecules are twisted 90° from a direction normal to the substrate, the vertical alignment (VA) mode in which liquid crystal molecules with a negative dielectric anisotropy are vertically oriented to the substrate surface, the in-plane switching (IPS) mode and fringe field switching (FFS) mode in which a horizontal electric field is applied to the liquid crystal layer by having the liquid crystal molecules being horizontally oriented to the substrate surface, and the like.
In VA mode, liquid crystal with a negative dielectric anisotropy is used, and display is performed by getting the liquid crystal molecules that are vertically oriented to the substrate surface to be horizontally oriented through a vertical electric field, but if a liquid crystal molecule is seen from a different angle, the perceived birefringence of the liquid crystal molecule changes, and thus causes a problem of having narrow viewing angles.
In IPS mode, display is performed by using a horizontal electric field that occurs between a pair of comb-shaped electrodes and taking advantage of the nature of liquid crystal molecules trying to become horizontally oriented to the electric field. In FFS mode, display is performed by using a horizontal electric field that occurs between a common electrode and pixel electrodes with an insulating layer therebetween and taking advantage of the nature of liquid crystal molecules trying to become horizontally oriented to the electric field. The viewing angles are improved in IPS mode and in FFS mode, but it is difficult to obtain a contrast ratio similar to VA mode.
Furthermore, recently, there has been new research in controlling the driving of the liquid crystal in display devices that conventionally perform display by using a horizontal electric field, such as IPS mode or FFS mode devices, by generating an additional vertical electric field (see Patent Documents 1 and 2, for example).